I'm considering pressurizing the rocker shafts on  my '55 292. I know there are at least a couple of methods, pinching off the shaft drain tubes appearing to be the easiest. My concern is about possibly starving some other part of the engine for oil. It looks like the output of the passenger side shaft goes to the timing chain. I don't know where the oil from the driver side tube goes, distributor/oil pump drive gear maybe...? I'm pretty sure a few guys here have done this so I'd like to know what method you used and the results before I pull the trigger. TIA for any advice.

In reference to hardened valve seats.  I have owned at least a dozen classic cars in my lifetime.  I love working on older engines. With few exceptions, I built a new engine for each car I owned.  The question of whether to install hardened valve seats has come up numerous times.  The logic is always that gas without lead will beat out the seats.  Some heads were beat up so bad by the time I got to them I had no choice. Others, like my current engine were pristine. 

I once owned a "G" code 406 Galaxie and a couple of 427 powered cars. Back then I bought boxes of lead additive to keep them running.  Today, I use Florida high test pump unleaded in my classic cars.   I hold the compression to about 9 to one. I time my engines correctly and they don't knock.   Since they started adding alcohol to the gas, I have not experience any damage from unleaded gas in any of my engines.  My current machinist agrees. He advised me not to install new seats in my Y-Block heads.  Keep in mind that I only drive my cars on nice days and to cruises.  If I was to build an engine to make a cross country trip, I would install new seats.  If nothing else, it would make me feel better.

new seats in eczG heads is a big risk as there is. very little cast left to hold them in place.in propane and natural gas engines you need stelight valves and seats.
I have herd from a number of machine shops that the alcahaul additives  that are in our gas helps.a easier solution is small amount  of engine oil in the gas at every fill, like 2 ounces.
  the so-called hardened seats in small block fords is heat the heads and quench them, looks good but rather question the hardness

I agree with FL-PHIL. Hard seats not necessary on lightly loaded, low speed engines.
Except I've started using Stabil 360 lately and I've always added some type of top end lubricant to the gas every so often out of habit.

"FREE SAMPLE"

Thats all I use on my engines, that stuff works good.  My 56 would normally get 3 weeks before the humidity here would result in separation of ethanol and fuel in the tank.  I started using the Stabil 360 and I can go a good 7 or 8 months without separation but the gas does get weak.

I also toss a bottle of Redline lead subsitute as well as my engine is original from '56 and I do plan on a complete rebuild with harden seats but my grandfather drove this car hard though foot always on the floor and it still running but lead gas was as far as i could tell was still avaliable in the early 1980s at some stations so maybe that is what saved this engine.

1956 Ford Fairlane Town Sedan - 292 Y8 - Ford-O-Matic - 155,000 mi

I think it's wise to go with hardened exhaust valve seats while the engine is being rebuilt. I know that "G" heads can crack between seats, but I have no direct knowledge of that occurring while installing hardened seats. I suppose it has much to do with the condition of the heads and who is doing the work. Having to baby it while driving can be stressful and takes the fun out of the experience. If in doubt, ask the man who knows. His name is Ted.